This invention relates generally to battery changing systems for electric battery-powered vehicles and more particularly to battery changing systems for electric battery-powered underground mining vehicles having a main frame and a battery support attached to the main frame.
Underground mining vehicles such as scoops, haulers, equipment movers, etc., powered by electric batteries are well known in the art. In the present battery technology, a fully charged battery normally provides electrical energy for the operation of an underground mining vehicle during one working shift of eight hours. The time necessary for charging a battery is about eight hours, and a cooling period of eight hours after the charging is usually recommended for improving the battery performance. Thus, the battery of a vehicle working more than one shift in a 24 hour period has to be charged after every shift. However, for continuous operation of a battery-powered vehicle after the battery has been discharged requires replacement by a charged battery.
Usually, the electric battery of an underground mining vehicle is arranged in a heavy steel-plate battery tray located at the rear section of the vehicle for acting as a counterweight to the useful load which is normally supported by the front section of the vehicle. The battery tray protects the battery against physical damage during the operation of the vehicle as well as during the changing of the battery. However, if the battery case itself is strong enough to protect the battery, then a separate battery tray may not be necessary. Since different arrangements of the battery may be employed, for simplicity of the description, the term "battery"is used to designate the whole exchangeable battery set, including the battery tray, if the battery is arranged in such a tray.
During operation of the vehicle, the battery is somehow secured to the structure of the vehicle which supports the battery. However, the vehicle has a battery changing system, usually using hydraulic power, for moving the battery up and down during a battery changing operation. The combination of the vertical motion of the battery provided by the battery changing system and the horizontal motion of the vehicle itself, enables the operator to unload the discharged battery from the vehicle onto a stand of a battery charging station, and to load a fresh battery from a stand of the battery charging station onto the vehicle.
There are generally two different types of battery changing systems, in relation with the battery support, which are well known in the art. In the first type, the battery lays on the bottom plate of the vehicle main frame, which bottom plate is uninterrupted or cut in a "U" shape. Two rigid vertical hydraulic cylinders, acting upon horizontal brackets on the left and right sides of the battery, move the battery up and down during a battery changing operation. The major disadvantage of this first type battery changing system is that the battery cannot be moved in a position lower than its normal position on top of the vehicle bottom plate. In the second type battery changing system the battery is loaded on and secured to a battery support, such as a fork, or a platform, or a "U" shaped structure, etc., which battery support, under the action of vertical hydraulic cylinders, moves up and down during a battery changing operation. The battery support is guided to move in the vertical direction by two parallel members attached firmly to the main frame of the vehicle. This second type of battery changing system is similar to the well known load-lifting system of a fork-lift truck. The major disadvantages of this second type battery changing systems are: first, the vertical travel of the battery is very short, because the lengths of the vertical hydraulic cylinders and parallel guides are limited by the height of the vehicle main frame, which in most cases is very short; and second, the parallel guides of the battery support are complicated and unreliable because it is difficult to keep them clean in an underground mine environment.
The foregoing illustrates limitations known to exist in present battery changing systems. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.